Valve timing adjusting apparatus

ABSTRACT

A valve timing adjusting apparatus includes a driving-side rotor, a driven-side rotor, a sun gear, and a planet gear. The driving-side rotor is rotatable synchronously with the crankshaft. The driven-side rotor is received in the driving-side rotor and rotatable synchronously with a camshaft. The sun gear is rotatable integrally with the driving-side rotor. The planet gear moves epicyclically relative to the sun gear. The driving-side rotor includes a peripheral wall member and a bottom wall member. One of the sun gear and the bottom wall member is fitted with an inner peripheral side of one axial end portion of the peripheral wall member. The other one is fitted with an outer peripheral side of the other axial end portion of the peripheral wall member.

CROSS REFERENCE TO RELATED APPLICATION

This application is based on and incorporates herein by referenceJapanese Patent Application No. 2008-29433 filed on Feb. 8, 2008.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a valve timing adjusting apparatuscapable of adjusting timing of a valve that is opened and closed by acamshaft through transmission of an engine torque from a crankshaft ofan internal combustion engine.

2. Description of Related Art

A conventional valve timing adjusting apparatus is known to obtain arequired valve timing by changing a relative phase relation between adriving-side rotor and a driven-side rotor. In the above, thedriving-side rotor is rotatable synchronously with a crankshaft, and thedriven-side rotor is rotatable synchronously with a camshaft. The aboverelative phase relation between the rotors is named as an “inter-rotorphase” in the present specification.

For example, FIG. 10 in JP-A-2007-255412 (corresponding to FIG. 10 inUS20070199531) discloses a valve timing adjusting apparatus that has adriving-side rotor, a driven-side rotor having a planet gear, and a sungear. The driving-side rotor has a hollow cylindrical shape with abottom and receives the driven-side rotor within a peripheral wallportion thereof. The sun gear is fixed coaxially with the driving-siderotor on a side of the driving-side rotor opposite from the bottom wallportion of the driving-side rotor. Also, the sun gear is rotatableintegrally with the driving-side rotor. The planet gear of thedriven-side rotor is in mesh with the sun gear. In the aboveconfiguration, an epicyclic motion of the planet gear changes theinter-rotor phase between the rotors.

In the apparatus shown in JP-A-2007-255412 (FIG. 10), the driving-siderotor serving as a sprocket is engaged with or is in mesh with anannular timing chain that is engaged with the crankshaft such that thetiming chain extends between and drivingly connects the driving-siderotor and the crankshaft. As a result, the timing chain transmits anengine torque between the driving-side rotor and the crankshaft. Thedriving-side rotor has a tubular shape with a bottom, and a bottom wallportion of the driving-side rotor has multiple teeth that are engagedwith the timing chain. As a result, the driving-side rotor has a complexshape as a whole. In order to produce the above complicated driving-siderotor, for example, it is required to perform a complicated operation,such as extensively machining a column-molded blank, and therebyproductivity may deteriorate disadvantageously.

In order to improve the productivity of the driving-side rotor, theinventors of the present invention have studied a technique, in whichthe driving-side rotor is made of separate two components (a peripheralwall portion and a bottom wall portion) that are coaxially fixed witheach other. The driving-side rotor made as above has a tubular shape.Because each of the two components are separate from one another in theformation process, the formation of each component is effectivelyfacilitated. However, it is found that the bottom wall portion and thesun gear may be displaced from each other when the engine torque istransmitted thereto because of a certain configuration, in which the sungear, which is in mesh with the planet gear, and the bottom wallportion, which is engaged with the timing chain, are coaxially with eachother with the peripheral wall portion interposed therebetween. Theabove possible displacement of the bottom wall portion and the sun gearmay twist the peripheral wall portion interposed therebetween, andthereby the peripheral wall portion may deform in the radial direction.As a result, the unwanted change of the inter-rotor phase between therotors may occur, and thereby the unwanted change in valve timing mayoccur disadvantageously.

SUMMARY OF THE INVENTION

The present invention is made in view of the above disadvantages. Thus,it is an objective of the present invention to address at least one ofthe above disadvantages.

To achieve the objective of the present invention, there is provided avalve timing adjusting apparatus for adjusting timing of a valve that isopened and closed by a camshaft through transmission of an engine torquefrom a crankshaft of an the internal combustion engine, the valve timingadjusting apparatus including a driving-side rotor, a driven-side rotor,a sun gear, and a planet gear. The driving-side rotor is rotatablesynchronously with the crankshaft by transmission of the engine torquethrough an annular torque transmission member that extends between thecrankshaft and the driving-side rotor. The driving-side rotor includes aperipheral wail member and a bottom wall member. The bottom wall memberis fastened coaxially to the peripheral wall member and connected withthe torque transmission member. The driven-side rotor is received in thedriving-side rotor and rotatable synchronously with the camshaft. Thesun gear is fastened coaxially to the peripheral wall member androtatable integrally with the driving-side rotor. The planet gear is inmesh with the sun gear and moves epicyclically with respect to the sungear such that a relative phase between the driving-side rotor and thedriven-side rotor is changed. One of the sun gear and the bottom wallmember is fitted with an inner peripheral side of one axial end portionof the peripheral wall member. The other one of the sun gear and thebottom wall member is fitted with an outer peripheral side of the otheraxial end portion of the peripheral wall member.

To achieve the objective of the present invention, there is alsoprovided a valve timing adjusting apparatus for adjusting timing of avalve that is opened and closed by a camshaft through transmission of anengine torque from a crankshaft of an the internal combustion engine,the valve timing adjusting apparatus including a driving-side rotor, adriven-side rotor, a sun gear, and a planet gear. The driving-side rotoris rotatable synchronously with the crankshaft. The driving-side rotorincludes a peripheral wall member and a bottom wall member that isfastened coaxially to the peripheral wall member. The bottom wall memberis coupled with a torque transmission member that extends between thecrankshaft and the driving-side rotor. The bottom wall member receivesthe engine torque transmitted through the torque transmission member.The driven-side rotor is received in the driving-side rotor androtatable synchronously with the camshaft. The sun gear is fastenedcoaxially to the peripheral wall member and rotatable integrally withthe driving-side rotor. The planet gear is in mesh with the sun near andmoves epicyclically with respect to the sun gear such that a relativephase between the driving-side rotor and the driven-side rotor ischanged. The peripheral wall member includes one axial end portion thatextends in a longitudinal direction of the driving-side rotor, and theone axial end portion defines a first fitting hole therein that has aradially inner contact surface. One of the sun gear and the bottom wallmember has a first fitting projection that extends in the longitudinaldirection of the driving-side rotor, and the first fitting projectionhas a radially outer contact surface. The first fitting projection isfitted into the first fitting hole such that the radially inner contactsurface of the first fitting hole is opposed to the radially outercontact surface of the first fitting projection in a radial direction ofthe driving-side rotor. The peripheral wall member includes the otheraxial end portion that serves as a second fitting projection extendingin the longitudinal direction of the driving-side rotor, and the secondfitting projection has a radially outer contact surface. The other oneof the sun gear and the bottom wall member defines a second fitting holetherein that has a radially inner contact surface. The second fittingprojection is fitted into the second fitting hole such that the radiallyinner contact surface of the second fitting hole is opposed to theradially outer contact surface of the second fitting projection in theradial direction of the driving-side rotor

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, together with additional objectives, features andadvantages thereof, will be best understood from the followingdescription, the appended claims and the accompanying drawings in which:

FIG. 1 is a cross-sectional view taken along line I-I in FIG. 2illustrating a basic configuration of a valve timing adjusting apparatusaccording to the first embodiment of the present invention;

FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1;

FIG. 3 is a cross-sectional view taken along line III-III in FIG. 1;

FIG. 4 is a cross-sectional view illustrating an enlarged phaseadjustment mechanism in FIG. 1;

FIG. 5 is a cross-sectional view illustrating an enlarged phaseadjustment mechanism of a valve timing adjusting apparatus according tothe second embodiment of the present invention; and

FIG. 6 is a cross-sectional view illustrating a phase adjustmentmechanism of a valve timing adjusting apparatus according to the thirdembodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Multiple embodiments of the present invention will be described withreference to accompanying drawings. Note that, components in one of theembodiments that are similar to components in the other embodiment willbe indicated by the same numerals, and thereby the overlappedexplanation thereof will be omitted.

First Embodiment

FIG. 1 shows a valve timing adjusting apparatus 1 according to the firstembodiment of the present invention. The valve timing adjustingapparatus 1 is mounted on a vehicle, and more specifically, the valvetiming adjusting apparatus 1 is mounted on a transmission system thattransmits an engine torque to a camshaft 2 from a crankshaft (not shown)of an internal combustion engine. It should be noted that in the presentembodiment the camshaft 2 opens and closes an intake valve (not shown)that serves as a “valve” of the internal combustion engine throughtransmission of the engine torque, and thereby the valve timingadjusting apparatus 1 adjusts valve timing of the intake valve.

(Basic Configuration)

A basic configuration of the valve timing adjusting apparatus 1 of thefirst embodiment will be described below. The valve timing adjustingapparatus 1 includes an electric motor 4, an energization controlcircuit unit 7, and a phase adjustment mechanism 8.

The electric motor 4 is, for example, a brushless motor, and includes amotor case 5 and a motor shaft 6. The motor case 5 is fixed to afixation part of an internal combustion engine, which is immovablerelative to the engine, and the motor shaft 6 is supported by the motorcase 5 rotatably in normal and reverse directions. The energizationcontrol circuit unit 7 includes a driver and a microcomputer thatcontrols the driver. The energization control circuit unit 7 is providedoutside and/or inside the motor case 5, and is electrically connectedwith the electric motor 4. The energization control circuit unit 7controls energization of the motor 4 in order to rotate the motor shaft6.

The phase adjustment mechanism 8 includes a driving-side rotor 10, a sungear 12, a driven-side rotor 20, a planet gear carrier 40, and a planetgear 50.

As shown in FIGS. 1 to 3, the driving-side rotor 10 has a hollowcylindrical shape with a bottom, and the sun gear 12 has a hollowcylindrical shape with a bottom. The driving-side rotor 10 and the sungear 12 are fixed coaxially with each other in a state where openingportions of the driving-side rotor 10 and the sun gear 12 overlap witheach other in an axial direction. In the above way, the driving-siderotor 10 and the sun gear 12 define therebetween a reception space 14that receives the other components 20, 40, 50 of the phase adjustmentmechanism 8.

The driving-side rotor 10 has multiple teeth 15 that are arranged oneafter another in a rotational direction, and the multiple teeth 15projects radially outwardly. An annular timing chain 16 is engaged withthe teeth 15 of the driving-side rotor 10 and with multiple teeth (notshown) of the crankshaft, and thereby the timing chain 16 extendsbetween and drivingly connects the driving-side rotor 10 and thecrankshaft. The above coupling enables the transmission of the enginetorque of the crankshaft to the driving-side rotor 10 through the timingchain 16 and causes the driving-side rotor 10 to rotate integrally withthe sun gear 12 and synchronously with the crankshaft. The rotationaldirection of the driving-side rotor 10 and the sun gear 12 correspondsto a clockwise direction in FIGS. 2, 3.

As shown in FIGS. 1, 2, the sun gear 12 includes a driving-side internalgear 18 on a radially inner side of a peripheral wall portion of the sungear 12, and the driving-side internal gear 18 defines an addendumcircle located on a radially inner side of a root circle.

As shown in FIGS. 1, 3, the driven-side rotor 20 has a hollowcylindrical shape with a bottom, and is concentrically fitted with thedriving-side rotor 10 on an inner peripheral side of the driving-siderotor 10. The driven-side rotor 20 has a connection member 21 on abottom wall portion of the driven-side rotor 20, and the connectionmember 21 is coaxially coupled with the camshaft 2 through a threadedmember. The above coupling enables the driven-side rotor 20 to rotatesynchronously with the camshaft 2 and to rotate with respect to thedriving-side rotor 10. The rotational direction of the driven-side rotor20 corresponds to the clockwise direction in FIG. 3 similar to thedriving-side rotor 10.

The driven-side rotor 20 includes a driven-side internal gear 22 on aradially inner side of the peripheral wall portion, and the driven-sideinternal gear 22 defines an addendum circle on a radially inner side ofa root circle. The driven-side internal gear 22 has an inner diametersmaller than an inner diameter of the driving-side internal gear 18, andthe number of teeth of the driven-side internal gear 22 is smaller thanthe number of teeth of the driving-side internal gear 18. Thedriven-side internal gear 22 is positioned away from the driving-sideinternal gear 18 in a longitudinal direction.

As shown in FIGS. 1 to 3, the planet gear carrier 40 generally has atubular shape and has an inner peripheral surface that serves as aninput portion 41. The input portion 41 is concentrically providedrelative to the rotors 10, 20 and the motor shaft 6. The input portion41 has a fitting groove 42 that is configured to be fitted with acoupling joint 43. The coupling joint 43 connects the motor shaft 6 withthe planet gear carrier 40. The coupling enables the planet gear carrier40 to rotate together with the motor shaft 6, and also to rotate withrespect to the driving-side rotor 10 and the sun gear 12.

The planet gear carrier 40 has an outer peripheral surface, which iseccentric with respect to the input portion 41, and which serves as aneccentric portion 44. The eccentric portion 44 is concentrically fittedinto a central hole 51 of the planet gear 50 through a bearing 45. Dueto the above configuration, the eccentric portion 44 supports the planetgear 50 in order to enable an epicyclic motion of the planet gear 50 inaccordance with a rotation of the planet gear carrier 40 with respect tothe sun gear 12. In the epicyclic motion of the present embodiment, theplanet gear 50 rotates about an eccentric axis of the eccentric portion44, and also the planet gear 50 revolves relative to the sun gear 12 inthe rotational direction of the planet gear carrier 40. In other words,the planet gear 50 rotates epicyclically with respect to the sun gear12.

The planet gear 50 has a shouldered hollow cylindrical shape, and morespecifically, the planet gear 50 has a large-diameter section and asmall-diameter section that has a diameter smaller than that of thelarge-diameter section. Thus, the planet gear 50 defines a driving-sideexternal gear 52 at the large-diameter section and a driven-sideexternal gear 54 at the small-diameter section. Each of the driving-sideexternal gear 52 and driven-side external gear 54 defines an addendumcircle on a radially outer side of a root circle. The driving-sideexternal gear 52 has the number of teeth that is smaller than the numberof teeth of the driving-side internal gear 18 by a certain number. Also,the number of teeth of the driven-side external gear 54 is smaller thanthe number of teeth of the driven-side internal gear 22 by the numberidentical with the above certain number. The driving-side external gear52 is provided on a radially inner side of the driving-side internalgear 18 and in mesh with the driving-side internal gear 18 Also, thedriven-side external gear 54 is displaced from the driving-side externalgear 52 toward the connection member 21. The driven-side external gear54 is provided on a radially inner side of the driven-side internal gear22 and in mesh with the driven-side internal gear 22.

The phase adjustment mechanism 8 gears to the rotors 10, 20 as above andadjusts an inter-rotor phase, which is a relative phase relation of thedriven-side rotor 20 with respect to the driving-side rotor 10, inaccordance with a rotational state of the motor shaft 6.

Specifically, in a case, where the planet gear carrier 40 is not rotatedwith respect to the sun gear 12 because the motor shaft 6 rotates at thespeed that is equivalent to the rotational speed of the driving-siderotor 10, the epicyclic motion of the planet gear 50 is not caused.Accordingly, the planet gear 50 rotates together with the rotors 10, 20.As a result, the inter-rotor phase is not changed, and accordingly, thevalve timing is held.

In contrast, in a case, where the planet gear carrier 40 rotatesrelative to the sun gear 12 in an advance direction because the motorshaft 6 rotates at a speed higher than the rotational speed of thedriving-side rotor 10, the epicyclic motion of the planet gear 50 iscaused. Accordingly, the driven-side rotor 20 rotates relative to thedriving-side rotor 10 in the advance direction. As a result, theinter-rotor phase is changed in the advance direction, and accordinglythe valve timing is advanced.

Also, in another case, where the planet gear carrier 40 rotates relativeto the sun gear 12 in a retard direction because the motor shaft 6rotates in a reverse direction or rotates at a speed lower than therotational speed of the driving-side rotor 10, the epicyclic motion ofthe planet gear 50 is caused. Accordingly, the driven-side rotor 20rotates relative to the driving-side rotor 10 in the retard direction.As a result, the inter-rotor phase is changed in the retard direction,and accordingly the valve timing is retarded.

(Characteristic Part)

Characteristic part of the first embodiment will be described.

(Fastening Structure of Driving-Side Rotor and Sun Gear)

As shown in FIG. 1, the driving-side rotor 10 includes a metal bottomwall member 100, a metal peripheral wall member 110, and threadedmembers 120.

As shown in FIG. 4, the bottom wall member 100 has an annular plateshape and has a thick wall. The bottom wall member 100 constitutes asprocket that has the teeth 15 engaged with the timing chain 16. Thebottom wall member 100 has a fitting hole 102 defined at a radial centerthereof. The fitting hole 102 is a hole having a bottom surface 104 andopens at one axial end surface 101 of the bottom wall member 100. Also,the bottom wall member 100 has a through hole 105 defined at the radialcenter thereof. The through hole 105 opens at the other axial endsurface 103 of the bottom wall member 100 and at the bottom surface 104of the fitting hole 102 and receives the camshaft 2.

The peripheral wall member 110 has a shouldered or stepped hollowcylindrical shape that has a different diameter at a different positionin the longitudinal direction. The peripheral wall member 110 has oneaxial end portion 111 having a smaller diameter than the other part ofthe peripheral wall member 110, and the one axial end portion 111 ispress-fitted into the fitting hole 102 of the bottom wall member 100.The one axial end portion 111 has a radially outer contact surface, andthe fitting hole 102 has a radially inner contact surface. Thus, in astate, where the one axial end portion 111 is press-fitted into thefitting hole 102 of the bottom wall member 100, the radially innercontact surface of the fitting hole 102 is opposed to the radially outercontact surface of the axial end portion 111 in a radial direction ofthe driving-side rotor 10. In other words, the one axial end portion 111of the peripheral wall member 110 has an outer peripheral side that ispress-fitted with the bottom wall member 100. Due to the above fitting,the peripheral wall member 110 defines therein a space 14 a, which is apart of the reception space 14, as shown in FIGS. 3, 4. The space 14 areceives an entirety of the driven-side rotor 20 and part of each of theplanet gear carrier 40 and the planet gear 50. Also, as shown in FIGS.2, 4, the peripheral wall member 110 has a fitting hole 114 defined at aradial center thereof. The fitting hole 114 is a hole with a bottom andopens at an end surface 113 of the other axial end portion 112. Theother axial end portion 112 has a diameter greater than that of the oneaxial end portion 111, and is located on a side of the peripheral wallmember 110 opposite from the one axial end portion 111 in thelongitudinal direction.

As shown in FIGS. 3, 4, each of the threaded members 120 is made of ametal bolt, and the threaded members 120 are provided at multiplepositions. The bottom wall member 100 and the peripheral wall member 110are arranged coaxial with each other, and the threaded members 120 areprovided at predetermined positions of the wall members 100, 110 in therotational direction in order to fasten the bottom wall member 100 withthe peripheral wall member 110 in the above coaxial state. As above, thebottom wall member 100, the peripheral wall member 110, and the threadedmembers 120 constitute the driving-side rotor 10 having a hollowcylindrical shape with a bottom.

As shown in FIGS. 2, 4, the sun gear 12 includes a fitting projection130 having a hollow cylindrical shape at an opening portion thereof andthe fitting projection 130 is press-fitted into the fitting hole 114 ofthe peripheral wall member 110. The fitting projection 130 has aradially outer contact surface, and the fitting hole 114 has a radiallyinner contact surface. Thus, in a state, where the fitting projection130 of the sun gear 12 is press-fitted into the fitting hole 114 of theother axial end portion 112 of the peripheral wall member 110, theradially inner contact surface of the fitting hole 114 is opposed to theradially outer contact surface of the fitting projection 130 in theradial direction of the driving-side rotor 10. In other words, the sungear 12 is press-fitted with an inner peripheral side of the other axialend portion 112 of the peripheral wall member 110. Due to the abovefitting, the sun gear 12 defines a space 14 b, which is another part ofthe reception space 14, at an inner peripheral side of the driving-sideinternal gear 18. The space 14 b is configured to receive the remainingof each of the planet gear carrier 40 and the planet gear 50, which isnot received by the space 14 a. The sun gear 12 is fastened togetherwith the bottom wall member 100 and the peripheral wall member 110 bythe multiple threaded members 120 at multiple positions in therotational direction. Thus, the sun gear 12 is fastened coaxially withthe peripheral wall member 110. In other words, in the presentembodiment, the sun gear 12 is arranged coaxially with the bottom wallmember 100, and the peripheral wall member 110 is provided between thesun gear 12 and the bottom wall member 100 in the longitudinaldirection.

(Stopper Structure)

As shown in FIG. 3, the peripheral wall member 110 is provided withadvance stopper surfaces 140 to 143 extending from an inner peripheralsurface 116 of the peripheral wall member 110 in a generally radiallyinward direction and arranged circumferentially or in the rotationaldirection one after another at multiple positions of the innerperipheral surface 116. Thus, each of the advance stopper surfaces 140to 143 has a step surface shape as shown in FIG. 3. Also, the peripheralwall member 110 has retard stopper surfaces 150 to 153 extending fromthe inner peripheral surface 116 in the generally radially inwarddirection and arranged in the rotational direction one after another atmultiple positions of the inner peripheral surface 116. Thus, each ofthe retard stopper surfaces 150 to 153 has a step surface shape. Each ofthe retard stopper surfaces 150 to 153 is spaced apart in the rotationaldirection from a corresponding one of the advance stopper surfaces 140to 143. As shown in FIG. 3, the retard stopper surface 150 is opposed tothe advance stopper surface 140, the retard stopper surface 151 isopposed to the advance stopper surface 141, the retard stopper surface152 is opposed to the advance stopper surface 142, and the retardstopper surface 153 is opposed to the advance stopper surface 143.

As shown in FIGS. 1, 3, the driven-side rotor 20 is provided withstopper projections 160 to 163 that projects from the peripheral wallportion of the driven-side rotor 20 in the radially outward direction ofthe driven-side internal gear 22. Also, the stopper projections 160 to163 are arranged at multiple positions of the peripheral wall portion inthe rotational direction. Each of the stopper projections 160 to 163 ispositioned between the corresponding one of pairs of the advance stoppersurfaces 140 to 143 and the retard stopper surfaces 150 to 153. Morespecifically, the stopper projection 160 is provided between the advancestopper surface 140 and the retard stopper surface 150, for example.

In the present embodiment, in a state, where the stopper projection 160contacts the advance stopper surface 140 that is positioned on anadvance side of the stopper projection 160 in the rotational direction,the driven-side rotor 20 is limited from rotating relative to thedriving-side rotor 10 in the advance direction. In other words, thechange of the inter-rotor phase in the advance direction is restricted.In contrast, in a state, where the stopper projection 160 contacts theretard stopper surface 150 that is positioned on a retard side of thestopper projection 160 in the rotational direction, the driven-siderotor 20 is limited from rotating relative to the driving-side rotor 10in the retard direction. In other words, the change of the inter-rotorphase in the retard direction is restricted. As above, the group of theadvance stopper surface 140, the retard stopper surface 150, and thestopper projection 160 function as a phase change restriction in anormal operation.

In an abnormal case, where there is a failure in the above normal groupof components 140, 150, 160, a first alternative group including thestopper surfaces 141, 151 and the stopper projection 161, a secondalternative group including the stopper surfaces 142, 152 and thestopper projection 162, and a third alternative group including thestopper surfaces 143, 153 and the stopper projection 163 mayalternatively function as the above phase change restriction of thenormal group.

(Method for Manufacturing Bottom Wall Member and Peripheral Wall Member)

Each of the bottom wall member 100 and the peripheral wall member 110 ofthe driving-side rotor 10 is formed by a cutting operation (machiningoperation) of a molded body made through a near net shape technique.

More specifically, in the formation process of the bottom wall member100, firstly, a powder metallurgy material is molded and sintered suchthat the sintered body has a annular plate shape similar to the finalshape of the finished product of the bottom wall member 100. As above, abottom wall member blank is formed to serve as the near net shape moldedbody. Then, the cutting operation is performed to a peripheral surfaceand a end surface of the bottom wall member blank, and thereby thebottom wall member 100 having the multiple teeth 15 and the holes 102,105 is completed.

Also, in the forming process of the peripheral wall member 110, firstly,a powder metallurgy material is molded and sintered such that thesintered body has a hollow cylindrical shape similar to the final shapeof the finished product of the peripheral wall member 110. As above, aperipheral wall member blank is formed to serve as the near net shapemolded body. Then, a peripheral surface and an end surface of theperipheral wall member blank is cut, and thereby the peripheral wallmember 110 having the hole 114 and the stopper surfaces 140 to 143, 150to 153 is completed.

The powder metallurgy material used for forming the bottom wall member100 and the peripheral wall member 110 may be selected from variousmetal materials in accordance with specifications. For example, in thepresent embodiment, alloy steel powder including copper is employed asthe powder metallurgy material. Also, in the present embodiment, the sungear 12, the driven-side rotor 20, the planet gear carrier 40, and theplanet gear 50 may be also formed by the cutting operation of the nearnet shape molded body similar to the case for the bottom wall member 100and the peripheral wall member 110.

In the above described first embodiment, the bottom wall member 100 andthe peripheral wall member 110 are separate bodies and are fastened toeach other to constitute the driving-side rotor 10. It is possible toeasily form the bottom wall member 100 and the peripheral wall member110 by the cutting of the near net shape molded body. More specifically,the stopper surfaces 140 to 143, 150 to 153 having the step surfaceshape are provided on the inner peripheral surface 116 of the peripheralwall member 110. Because the peripheral wall member 110 is separate fromthe bottom wall member 100, the above stopper surfaces 140 to 143, 150to 153 are further easily made by the cutting operation. Furthermore, inthe first embodiment, the threaded member 120 fastens the bottom wallmember 100 with the peripheral wall member 110 in order to form thedriving-side rotor 10. Because the above threaded member 120 is alsoused to fasten the sun gear 12 with the driving-side rotor 10, afastening structure of the driving-side rotor 10 and the sun gear 12 iseasily realized or obtained. In the first embodiment, productivity ofthe valve timing adjusting apparatus 1 is effectively improved.

Also, according to the first embodiment, the sun gear 12, which is inmesh with the planet gear 50, and the bottom wall member 100, which isengaged with the timing chain 16 transmitting the engine torque, areprovided coaxially with each other on opposite axial sides of theperipheral wall member 110. As a result, the sun gear 12 may bedisplaced relative to the bottom wall member 100 while transmitting theengine torque in the conventional art. However, the sun gear 12 isfitted with the inner peripheral side of the other axial end portion 112of the peripheral wall member 110, and the bottom wall member 100 isfitted with the outer peripheral side of the one axial end portion 111of the peripheral wall member 110. In other words, the sun gear 12 isfitted into the other axial end portion 112, and the one axial endportion 111 is fitted into the bottom wall member 100. As a result, evenwhen the peripheral wall member 110 receives a torsional force caused bythe displacement of the sun gear 12 relative to the bottom wall member100, one of the axial end portions 111, 112 is urged radially inwardlyby the other one of the axial end portions 111, 112, and thereby theperipheral wall member 110 is limited from deforming in the radialdirection. Furthermore, in the first embodiment, boundary surfacesbetween the sun gear 12 and the peripheral wall member 110 are pressfitted with each other. Also, the other boundary surfaces between thebottom wall member 100 and the peripheral wall member 110 are pressfitted with each other. Due to the above configuration, clearances thatotherwise allow the deformation of the axial end portions 112, 111 ofthe peripheral wall member 110 in the radial direction are substantiallyeliminated. Still more, in the first embodiment, because the components12, 100, 110 are fastened to each other commonly by the threaded members120, torsion of the peripheral wall member 110 cased by the displacementof the components 12, 100 is restricted by the threaded members 120.According to the first embodiment, even in a condition, where thedisplacement of the components 12, 100 from each other is prone to occurbecause of the engine torque highly efficiently transmitted through themultiple teeth 15 engaged with the timing chain 16, the unwanted changeof the inter-rotor phase caused by the deformation of the peripheralwall member 110 is effectively restricted as above, and thereby accuracyin adjustment of the valve timing is effectively improved.

In addition to the above, according to the first embodiment, when thestopper projection 160 of the driven-side rotor 20 contacts, in therotational direction, one of the stopper surfaces 140, 150 defined onthe inner peripheral surface 116 of the peripheral wall member 110,deformation of the peripheral wall member 110 in the radial directionmay occur in the conventional art. However, in the first embodiment, theperipheral wall member 110 is limited from deforming in the radialdirection as above, and thereby even when the stopper projection 160contacts either one of the stopper surfaces 140, 150, the unwantedchange of the inter-rotor phase is restricted. As a result, accuracy inadjustment of the valve timing is effectively improved.

It should be noted that in the first embodiment, the timing chain 16serves as a “torque transmission member”, and the threaded member 120serves as a “fastening member”. The fitting hole 114 serves as “firstfitting hole”, and the fitting projection 130 serves as “first fittingprojection”. Also, the fitting hole 102 serves as “second fitting hole”,and the axial end portion 111 serves as “second fitting projection”.

Second Embodiment

As shown in FIG. 5, the second embodiment of the present invention ismodification of the first embodiment. In the second embodiment, a metalbottom wall member 2100 constituting a driving-side rotor 2010 includesa fitting projection 2102 instead of the fitting hole 102. The fittingprojection 2102 has a hollow cylindrical shape defining therein acentral hole. The central hole corresponds to a part of the through hole105.

Also, a metal peripheral wall member 2110 constituting the driving-siderotor 2010 has a shouldered or stepped hollow cylindrical shape. Theshouldered hollow cylindrical shape has a different diameter at adifferent position of the shouldered hollow cylindrical shape in thelongitudinal direction. The peripheral wall member 2110 has one axialend portion 2111 and the other axial end portion 2112, and the one axialend portion 2111 has a diameter greater than that of the other axial endportion 2112. The peripheral wall member 2110 defines a fitting hole2114 with a bottom at a generally central part thereof, and the fittinghole 2114 opens at an end surface 2113 of the one axial end portion2111. The fitting projection 2102 of the bottom wall member 2100 ispress-fitted into the fitting hole 2114. In other words, the bottom wallmember 2100 is press-fitted with an inner peripheral side of the oneaxial end portion 2111 of the peripheral wall member 2110.

A sun gear 2012 defines a fitting hole 2014 with a bottom at a generallycentral part thereof. The fitting hole 2014 opens at one end surface2013 of the sun gear 2012. The fitting hole 2014 is press-fitted withthe other axial end portion 2112 of the peripheral wall member 2110. Inother words, the sun gear 2012 is press-fitted with an outer peripheralside of the other axial end portion 2112 of the peripheral wall member2110.

As above, in the second embodiment, in a state, where the peripheralwall member 2110 is provided between the bottom wall member 2100 and thesun gear 2012 in the longitudinal direction, the above components 2012,2100, 2110 are fastened coaxial with each other by the threaded member120 of the driving-side rotor 2010. Thus, the above components 2012,2100, 2110 are integral with each other. The bottom wall member 2100 isfitted with the inner peripheral side of the one axial end portion 2111of the peripheral wall member 2110, and the sun gear 2012 is fitted withthe outer peripheral side of the other axial end portion 2112 of theperipheral wall member 2110. Even when the peripheral wall member 2110receives a torsion force caused by the components 2100, 2012 that tendto be displaced from each other, the peripheral wall member 2110 islimited from deforming in the radial direction due to the mechanismsimilar to the first embodiment. Also, because the boundary surfaces ofthe components are pressed fitted with each other as above, a clearancethat otherwise enables the deformation of the peripheral wall member2110 is substantially eliminated similar to the first embodiment. Also,the threaded member 120 is capable of restricting the twist of theperipheral wall member 2110 similar to the first embodiment. As aresult, also in the second embodiment, the unwanted change of theinter-rotor phase caused by deformation of the peripheral wall member2110 is limited, and thereby it is possible to accurately adjust thevalve timing. In addition to the above, in the second embodiment, thebottom wall member 2100 and the peripheral wall member 2110 areseparately formed by the cutting operation of cutting the near net shapemolded body similar to the first embodiment. As a result, the extensivecutting operation is effectively avoided, and thereby productivity iseffectively improved. In the present embodiment, the fitting projection2102 serves as “first fitting projection”, and the fitting hole 2114serves as “first fitting hole”. Also, the axial end portion 2112 servesas “second fitting projection”, and the fitting hole 2014 serves as“second fitting hole”.

Third Embodiment

As shown in FIG. 6, the third embodiment of the present invention ismodification of the second embodiment. In the third embodiment, a metalperipheral wall member 3110 constituting a driving-side rotor 3010 has astraight hollow cylindrical shape that has a substantially constantdiameter over a length or in a longitudinal direction of thedriving-side rotor 3010. In other words, the peripheral wall member 3110has a hollow cylindrical shape extending straight in the longitudinaldirection of the peripheral wall member 3110. It should be noted thatthe peripheral wall member 3110 has the stopper surfaces 140 to 143, 150to 153 (not shown) at an inner peripheral surface of the peripheral wallmember 3110, and each of the stopper surfaces 140 to 143, 150 to 153 hasa step surface shape. In the present embodiment, for example, each ofthe above stopper surfaces 140 to 143, 150 to 153 has a shape thatextends straight in the longitudinal direction from one axial end to theother axial end of each stopper surface. Also, the inner peripheralsurface between the adjacent stopper surfaces has a shape that extendsstraight in the longitudinal direction from one axial end to the otheraxial end of the inner peripheral surface. Thus, the driving-side rotor3010 extends straight from the one axial end portion 2111 to the otheraxial end portion 2112 in the longitudinal direction of the driving-siderotor 3010.

According to the peripheral wall member 3110 having the above straightshape, it is more easy to execute the near net shape molding operationfor forming the peripheral wall member blank and the cutting operationof cutting the peripheral wall member blank compared with the case ofmolding or machining the shouldered member bank. As a result,productivity is substantially effectively improved.

Other Embodiment

Although the multiple embodiments of the present invention have beendescribed as above, the interpretation of the present invention is notlimited to the above embodiments. Thus, the present invention isapplicable to various embodiments provided that the various embodimentsdo not deviate from the gist of the present invention.

More specifically, “torque transmission member” that transmits theengine torque to the driving-side the rotors 10, 2010, 3010 may employ,for example, a timing belt that is engaged with the bottom wall member100, 2100 and with the multiple teeth 15, in place of the timing chain16.

In place of the above described press fitting, the fitting of the bottomwall member 100, 2100 with the peripheral wall member 110, 2110, 3110,and the fitting of the sun gear 12, 2012 with the peripheral wall member110, 2110, 3110 may be realized even when the boundary surfaces of theabove components are fitted with each other with a clearance definedtherebetween. Also, at least the bottom wall member 100, 2100 and theperipheral wall member 110, 2110, 3110 may be formed by cutting aalternative near net shape molded body formed by the other process otherthan the sintering of the powder metallurgy material. For example, thealternative near net shape molded body may be alternatively formed byforging a metal material.

The “fastening member” that fastens at least the bottom wall member 100,2100 and the peripheral wall member 110, 2110, 3110 may alternativelyemploy, for example, a rivet, or a pin in place of the threaded member120. Also, the sun gear 12, 2012 may be alternatively fastened to theperipheral wall member 110, 2110, 3110 by another “fastening member” inaddition to the “fastening member” that fastens the bottom wall member100, 2100 with the peripheral wall member 110, 2110, 3110.

In the above, the planet gear 50 gears to the sun gear 12, 2012 and tothe gear 22 of the driven-side rotor 20 in the phase adjustmentmechanism 8. However, the phase adjustment mechanism 8 may alternativelyhave another configuration, in which, an alternative planet gear gearsonly to a sun gear that is fastened to the driving-side the rotors 10,2010, 3010, for example. In the above alternative case, the driven-siderotor 20 is rotated relative to the driving-side the rotors 10, 2010,3010 in accordance with the epicyclic motion of the alternative planetgear. Also, the sun gear that is fastened to the driving-side the rotors10, 2010, 3010 is meshed with the planet gear through the internal gear18 as above. However, the sun gear may alternatively be meshed with theexternal gear of the planet gear.

In the above embodiments, the apparatus adjusts valve timing of theintake valve. However, the present invention may be applicable to anapparatus that adjusts valve timing of an exhaust valve serving as a“valve” and to an apparatus that adjusts valve timing of both the intakevalve and the exhaust valve.

Additional advantages and modifications will readily occur to thoseskilled in the art. The invention in its broader terms is therefore notlimited to the specific details, representative apparatus, andillustrative examples shown and described.

1. A valve timing adjusting apparatus for adjusting timing of a valvethat is opened and closed by a camshaft through transmission of anengine torque from a crankshaft of an the internal combustion engine,the valve timing adjusting apparatus comprising: a driving-side rotorthat is rotatable synchronously with the crankshaft by transmission ofthe engine torque through an annular torque transmission member thatextends between the crankshaft and the driving-side rotor, wherein: thedriving-side rotor includes a peripheral wall member and a bottom wallmember; and the bottom wall member is fastened coaxially to theperipheral wall member and connected with the torque transmissionmember; a driven-side rotor that is received in the driving-side rotorand rotatable synchronously with the camshaft; a sun gear that isfastened coaxially to the peripheral wall member and rotatableintegrally with the driving-side rotor; and a planet gear that is inmesh with the sun gear and moves epicyclically with respect to the sungear such that a relative phase between the driving-side rotor and thedriven-side rotor is changed, wherein: one of the sun gear and thebottom wall member is fitted with an inner peripheral side of one axialend portion of the peripheral wall member; and the other one of the sungear and the bottom wall member is fitted with an outer peripheral sideof the other axial end portion of the peripheral wall member.
 2. Thevalve timing adjusting apparatus according to claim 1, wherein: the oneof the sun gear and the bottom wall member is press fitted with theinner peripheral side of the one axial end portion of the peripheralwall member such that the one of the sun gear and the bottom wall memberis press fitted into the one axial end portion; and the other one of thesun gear and the bottom wall member is press fitted with the outerperipheral side of the other axial end portion of the peripheral wallmember such that the other axial end portion is press fitted into theother one of the sun gear and the bottom wall member.
 3. The valvetiming adjusting apparatus according to claim 1, wherein: thedriving-side rotor includes at least one fastening member that fastensthe peripheral wall member with the bottom wall member; and the at leastone fastening member fastens the sun gear together with the peripheralwall member and the bottom wall member.
 4. The valve timing adjustingapparatus according to claim 1, wherein: the bottom wall member is asprocket having a plurality of teeth that are engaged with the torquetransmission member.
 5. The valve timing adjusting apparatus accordingto claim 1, wherein: the peripheral wall member includes a stoppersurface at an inner peripheral surface of the peripheral wall member;and the stopper surface has a step surface shape that contacts thedriven-side rotor in a rotational direction such that change of therelative phase is limited.
 6. The valve timing adjusting apparatusaccording to claim 1, wherein: the peripheral wall member has a tubularshape extending straight in a longitudinal direction of the peripheralwall member.
 7. The valve timing adjusting apparatus according to claim1, wherein: each of the peripheral wall member and the bottom wallmember is formed by cutting a corresponding near net shape molded body.8. A valve timing adjusting apparatus for adjusting timing of a valvethat is opened and closed by a camshaft through transmission of anengine torque from a crankshaft of an the internal combustion engine,the valve timing adjusting apparatus comprising: a driving-side rotorthat is rotatable synchronously with the crankshaft, wherein: thedriving-side rotor includes a peripheral wall member and a bottom wallmember that is fastened coaxially to the peripheral wall member; thebottom wall member is coupled with a torque transmission member thatextends between the crankshaft and the driving-side rotor; and thebottom wall member receives the engine torque transmitted through thetorque transmission member; a driven-side rotor that is received in thedriving-side rotor and rotatable synchronously with the camshaft; a sungear that is fastened coaxially to the peripheral wall member androtatable integrally with the driving-side rotor; and a planet gear thatis in mesh with the sun gear and moves epicyclically with respect to thesun gear such that a relative phase between the driving-side rotor andthe driven-side rotor is changed, wherein: the peripheral wall memberincludes one axial end portion that extends in a longitudinal directionof the driving-side rotor, the one axial end portion defining a firstfitting hole therein that has a radially inner contact surface; one ofthe sun gear and the bottom wall member has a first fitting projectionthat extends in the longitudinal direction of the driving-side rotor,the first fitting projection having a radially outer contact surface;the first fitting projection is fitted into the first fitting hole suchthat the radially inner contact surface of the first fitting hole isopposed to the radially outer contact surface of the first fittingprojection in a radial direction of the driving-side rotor; theperipheral wall member includes the other axial end portion that servesas a second fitting projection extending in the longitudinal directionof the driving-side rotor, the second fitting projection having aradially outer contact surface; the other one of the sun gear and thebottom wall member defines a second fitting hole therein that has aradially inner contact surface; and the second fitting projection isfitted into the second fitting hole such that the radially inner contactsurface of the second fitting hole is opposed to the radially outercontact surface of the second fitting projection in the radial directionof the driving-side rotor.
 9. The valve timing adjusting apparatusaccording to claim 8, wherein: the first fitting projection is pressfitted into the first fitting hole; and the second fitting projection ispress fitted into the second fitting hole.
 10. The valve timingadjusting apparatus according to claim 8, wherein: the driving-siderotor includes at least one fastening member that fastens the peripheralwall member with the bottom wall member; and the at least one fasteningmember fastens the sun gear together with the peripheral wall member andthe bottom wall member.
 11. The valve timing adjusting apparatusaccording to claim 8, wherein: the bottom wall member is a sprockethaving a plurality of teeth that are engaged with the torquetransmission member.
 12. The valve timing adjusting apparatus accordingto claim 8, wherein: the peripheral wall member includes a stoppersurface at an inner peripheral surface of the peripheral wall member;and the stopper surface has a step surface shape that contacts thedriven-side rotor in a rotational direction such that change of therelative phase is limited.
 13. The valve timing adjusting apparatusaccording to claim 8, wherein: the peripheral wall member has a tubularshape extending straight from the one axial end portion to the otheraxial end portion in a longitudinal direction of the peripheral wallmember.
 14. The valve timing adjusting apparatus according to claim 8,wherein: each of the peripheral wall member and the bottom wall memberis formed by cutting a corresponding near net shape molded body.